The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.
There is a trend in electrochemical cell design that requires a development of new materials for energy storage technologies to allow for safe, economic and energy efficient batteries. A number of cyanide-based transition metal compounds used as cathodes have been developed for organic and aqueous electrolytes.
Recent developments regarding cyanide-bridged coordination polymer electrodes for aqueous-based electrolyte batteries have revealed promising results. However, many challenges must be have addressed before cyanide-based transition metal compounds may be safely, economically and used in an energy efficiently manner in an anode, especially in an anode operated in an electrochemical cell having high energy density. Relatively high electrochemical reaction potentials of cyanide-based transition metal anode materials typically result in relatively low full cell voltages, and therefore, energy densities.
For example, manganese hexacyanomanganate anode material has an electrochemical reaction potential of −0.7 V vs. the standard hydrogen electrode (SHE). The combination of such an anode material with a cathode material having a typical electrochemical reaction potential of about 1.0 V vs. SHE results in a battery cell having a voltage of about 1.7 V. This is a relatively low voltage in comparison to other batteries, such as lead acid or lithium-ion batteries, which may have a cell voltage greater than 2 V. The energy density of a battery cell is proportional to the cell voltage. Therefore, the relatively high electrochemical potential of such an anode material renders the material less attractive as an anode active material despite its potential advantages due to its electrochemical properties.
Previously reported compositions of matter for TMCCC materials include a crystal structure having interstitial water. One use of TMCCC materials is an electrode (e.g., an anode) of an electrochemical device, particularly devices having relatively extended cycle life. One goal of electrode material innovations is to invent and develop materials having improved electrochemical potentials (e.g., an anode material having a more negative electrochemical potential or a cathode having a more positive electrochemical potential) and having improved properties enhancing use of the electrode material in a physical electrode or electrochemical cell having a high energy density.
Such innovations may include a system, method, and articles of manufacture for an improved transition metal cyanide coordination compound (TMCCC) composition, an improved electrode including the composition, and a manufacturing method for the composition, and materials for improving an electrochemical potential for a TMCCC electrode.